{"cve":"CVE-2025-38523","nvd":{"published":"2025-08-16T12:15:27.667","modified":"2026-07-30T06:23:23.710","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: Fix the smbd_response slab to allow usercopy\n\nThe handling of received data in the smbdirect client code involves using\ncopy_to_iter() to copy data from the smbd_reponse struct's packet trailer\nto a folioq buffer provided by netfslib that encapsulates a chunk of\npagecache.\n\nIf, however, CONFIG_HARDENED_USERCOPY=y, this will result in the checks\nthen performed in copy_to_iter() oopsing with something like the following:\n\n CIFS: Attempting to mount //172.31.9.1/test\n CIFS: VFS: RDMA transport established\n usercopy: Kernel memory exposure attempt detected from SLUB object 'smbd_response_0000000091e24ea1' (offset 81, size 63)!\n ------------[ cut here ]------------\n kernel BUG at mm/usercopy.c:102!\n ...\n RIP: 0010:usercopy_abort+0x6c/0x80\n ...\n Call Trace:\n  <TASK>\n  __check_heap_object+0xe3/0x120\n  __check_object_size+0x4dc/0x6d0\n  smbd_recv+0x77f/0xfe0 [cifs]\n  cifs_readv_from_socket+0x276/0x8f0 [cifs]\n  cifs_read_from_socket+0xcd/0x120 [cifs]\n  cifs_demultiplex_thread+0x7e9/0x2d50 [cifs]\n  kthread+0x396/0x830\n  ret_from_fork+0x2b8/0x3b0\n  ret_from_fork_asm+0x1a/0x30\n\nThe problem is that the smbd_response slab's packet field isn't marked as\nbeing permitted for usercopy.\n\nFix this by passing parameters to kmem_slab_create() to indicate that\ncopy_to_iter() is permitted from the packet region of the smbd_response\nslab objects, less the header space.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-1188"],"references":["https://git.kernel.org/stable/c/43e7e284fc77b710d899569360ea46fa3374ae22","https://git.kernel.org/stable/c/87dcc7e33fc3dcb8ed32333cec016528b5bb6ce4","https://git.kernel.org/stable/c/f0dd353d47f7051afa98c6c60c7486831eb1a410"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:06:45.861874017+00:00"},"epss":{"cve":"CVE-2025-38523","score":0.00367,"percentile":0.30558,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}